Effects of clenbuterol hydrochloride on pulmonary gas exchange and hemodynamics in anesthetized horses.
Abstract: We evaluated the effects of clenbuterol HCl (0.8 micrograms/kg, of body weight, IV), a beta 2 agonist, on ventilation-perfusion matching and hemodynamic variables in anesthetized (by IV route), laterally recumbent horses. The multiple inert gas elimination technique was used to assess pulmonary gas exchange. Clenbuterol HCl induced a decrease in arterial oxygen tension (from 57.0 +/- 1.8 to 49.3 +/- 1.2 mm of Hg; mean +/- SEM) as a result of increased shunt fraction (from 6.6 +/- 2.1 to 14.4 +/- 3.1%) and ventilation to regions with high ventilation-perfusion ratios. In contrast, no changes in these variables were found in horses given sterile water. In horses given clenbuterol HCl, O2 consumption increased from 2.23 +/- 0.18 to 2.70 +/- 0.14 ml.min-1.kg-1, and respiratory exchange ratio decreased from 0.80 +/- 0.02 to 0.72 +/- 0.01. Respiratory exchange ratio and O2 consumption were not significantly modified in sterile water-treated (control) horses. Clenbuterol HCl administration was associated with increased cardiac index (from 57.4 +/- 4.0 to 84.2 +/- 6.3 ml.min-1.kg-1), decreased total peripheral vascular resistance (from 108.3 +/- 9.3 to 47.6 +/- 2.8 mm of Hg.s.kg.ml-1), and decreased pulmonary vascular resistance (from 31.3 +/- 3.8 to 13.6 +/- 0.7 mm of Hg.s.kg.ml-1). Our findings indicated that clenbuterol HCl may potentiate hypoxemia as a result of increased shunt fraction in horses anesthetized by the IV route, and caused changes in hemodynamic variables that were consistent with its ability to stimulate beta 2-adrenergic receptors.
Publication Date: 1993-05-01 PubMed ID: 8317772
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study evaluates how the drug clenbuterol hydrochloride impacts the oxygen and blood flow dynamics in anesthetized horses. The results indicate that the drug may exacerbate low oxygen levels in the blood of these horses and alter components of their cardiovascular system, in line with its known effects on certain chemical receptors in the body.
Introduction
- Clenbuterol HCl, a beta 2 agonist medication, was administered intravenously to anesthetized, laterally recumbent (lying on their side) horses in this research study.
- The aim was to investigate the effects of this drug on the balance between ventilation (movement of air into and out of the lungs) and perfusion (flow of blood to the lung tissue) and on certain hemodynamic (relating to the flow of blood) variables in these horses.
Research Method
- The study utilized the multiple inert gas elimination technique to measure pulmonary gas exchange, basically assessing how well the lungs were able to transfer oxygen into and remove carbon dioxide from the bloodstream.
Results of Clenbuterol HCl Administration
- The administration of Clenbuterol HCl resulted in a decrease in arterial oxygen tension, meaning the levels of oxygen in the bloodstream reduced.
- This was due to an increase in the ‘shunt fraction’ (where some of the blood in the lungs bypasses the normal gas exchange process) and increased ventilation to lung regions with high ventilation-perfusion ratios.
- Clenbuterol HCl also led to increased oxygen consumption, while the respiratory exchange ratio (the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed) decreased.
- Furthermore, the drug’s administration corresponded with an increased cardiac index (a measurement of the heart’s pumping capability), decreased total peripheral vascular resistance (the resistance to blood flow in the peripheral vessels), and decreased pulmonary vascular resistance (the resistance to blood flow in the lung vessels).
Conclusion
- The study concludes that Clenbuterol HCl may enhance hypoxemia (an abnormally low level of oxygen in the blood), as it increases the shunt fraction in horses anesthetized intravenously.
- Additionally, it causes alterations in hemodynamic variables that mirror its ability to stimulate beta 2-adrenergic receptors. These receptors, when activated, play a crucial role in relaxing smooth muscle, particularly in the airways and blood vessels, which corresponds with the observed changes in ventilation, perfusion, and cardiovascular dynamics.
Cite This Article
APA
Dodam JR, Moon RE, Olson NC, Exposito AJ, Fawcett TA, Huang YC, Theil DR, Camporesi E, Swanson CR.
(1993).
Effects of clenbuterol hydrochloride on pulmonary gas exchange and hemodynamics in anesthetized horses.
Am J Vet Res, 54(5), 776-782.
Publication
Researcher Affiliations
- Department of Anatomy, Physiological Sciences and Radiology, College of Veterinary Medicine, North Carolina State University, Raleigh 27606.
MeSH Terms
- Anesthesia, General / veterinary
- Animals
- Body Temperature / drug effects
- Cardiac Output / drug effects
- Clenbuterol / pharmacology
- Heart Rate / drug effects
- Hemodynamics / drug effects
- Horses / physiology
- Lung / drug effects
- Lung / physiology
- Oxygen Consumption / drug effects
- Pulmonary Circulation / drug effects
- Respiration / drug effects
- Vascular Resistance / drug effects
Citations
This article has been cited 2 times.- Henriquez AR, Snow SJ, Schladweiler MC, Miller CN, Dye JA, Ledbetter AD, Richards JE, Hargrove MM, Williams WC, Kodavanti UP. Beta-2 Adrenergic and Glucocorticoid Receptor Agonists Modulate Ozone-Induced Pulmonary Protein Leakage and Inflammation in Healthy and Adrenalectomized Rats. Toxicol Sci 2018 Dec 1;166(2):288-305.
- Casoni D, Spadavecchia C, Adami C. Cardiovascular changes after administration of aerosolized salbutamol in horses: five cases. Acta Vet Scand 2014 Aug 14;56(1):49.
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